2 layers
2 layers41 × 55.4 mm
TouchwheelSAO
todbot/TouchwheelSAO12Touchwheel SAO for Hackaday Supercon 2024
- Size
- 41 × 55.4 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 21
- Nets
- 26
- Pads
- 72
- Tracks, vias
- 194, 23
- Pours
- 3
- Routed
- Yes
- KiCad
- KiCad 8.0 (file 20240108)
- Created
- 9 Aug 2024
- Updated
- 11 Aug 2025
Overview
TouchwheelSAO is an open-source printed circuit board by todbot, from the todbot/TouchwheelSAO repository on GitHub, published under the GPL-3.0 licence. It is a 2-layer board of 41 × 55.4 mm with 21 parts on 26 nets, routed with 194 tracks and 23 vias.
It is built around the ATTINY816-MN and SK6812SIDE-A. Its parts include 9 resistors, 4 diodes, 2 capacitors, 2 connectors and 1 IC. It belongs with the lEDs and displays boards and the AVR (ATmega, ATtiny) boards of this library.
Main components
2
ATTINY816-MN
QFN-20-EP(3x3)-40℃~+105℃ 1.8V~5.5V 10bit 128Byte 18 20MHz 512Byte 8 Bit 8KB 8bit AVR Built-in FLASH Power-on reset (POR)、Undervoltage detection (BOR/LVD/LVR/LVI)、Watchdog reset、Built-in general-purpose timer、Hardware CRC、Calendar function、Touch function、Window watchdog (WWDG) VQFN-20-EP(3x3) Microcontrollers (MCU/MPU/SOC) ROHSMicrochip TechnologyMicrocontrollers (MCU/MPU/SOC)
SK6812SIDE-A
SMD-4P,4x1.6mm-40℃~+85℃ 0.6mA 1.6mm 120° 160mcd~320mcd 1kHz 2000V 240mcd~450mcd 2mm 3.7V~5.5V 460nm~470nm 4mm 520nm~535nm 620nm~625nm 697.5mcd~1162.5mcd 800Kbit/s Built-in power-on reset circuit Translucent Frosted Lens SMD-4P,4x1.6mm RGB LEDs(Built-in IC) ROHSOPSCO OptoelectronicsRGB LEDs(Built-In IC)
README
README.mdTouchwheelSAO
Capacitive touchweel SAO for Hackaday Supercon 2024
Features
- Three capacitive touch pads arranged in interleaved disk, builds on touchwheel0
- Three "Neopixel"-compatible side-light RGB LEDs that shine through the center
- Standard SAO pinout w/ I2C. Spare GPIO lines wired to UART TX/RX
- Finger position 0-255 readable via I2C, LEDs controllable via I2C. See register map for details
- One status LED on back of board
- ATtiny816-based, same as seesaw boards
- Easy compilation using standard Ardiuno toolchain and megaTinyCore
- Uses modified TouchyTouch captouch library, included
Production details
- View BOM
- View SCH PDF
- Production files: gerbers zip, bom csv, positions csv
Renders:
Production version (cat approved):
https://github.com/user-attachments/assets/31f27016-510a-4a7b-9d95-70a69f371cc3
Prototype Demo:
https://github.com/user-attachments/assets/b0e4c4f9-f228-49bc-8d6e-ceb53a960fb6
Prototype Renders
- Render2:
https://github.com/user-attachments/assets/08d6583a-afa1-4c01-aba5-ca108eea4f24
- Render1:
https://github.com/user-attachments/assets/c628ba94-1a07-43ad-b761-b3852f8f35f7
Notes:
- Related to touchwheel0
- Uses ATtiny816, using megaTinyCore for Arduino
- 9Sep2024: Originally designed for QFN, but SOIC requested. ATtiny816 comes in hilariously wide SOIC
- 16Sep2024: Back to QFN for ATtiny816 for JLC assembly.
- 16Sep2024: SAO header must be hand switched to be same side ("top") as SMD in positions.csv for JLC to assemble it correctly
Parts
21| Qty | Value | Footprint | References |
|---|---|---|---|
| 3 | 10k | Resistor_SMD:R_0603_1608Metric | R1, R2, R3 |
| 3 | 1M | Resistor_SMD:R_0603_1608Metric | R4, R5, R6 |
| 3 | SK6812SIDE | todbot_stuff:LED-SMD_4P-L4.0-W1.6-L | LED1, LED2, LED3 |
| 2 | 1k | Resistor_SMD:R_0603_1608Metric | R7, R9 |
| 2 | Fiducial | Fiducial:Fiducial_1mm_Mask2mm | FID1, FID2 |
| 1 | 100n | Resistor_SMD:R_0603_1608Metric | C2 |
| 1 | 10uF | Resistor_SMD:R_0603_1608Metric | C1 |
| 1 | 470 | Resistor_SMD:R_0603_1608Metric | R8 |
| 1 | ATtiny816-M | easyeda2kicad:UQFN-20_L3.0-W3.0-P0.40-BL-EP1.7 | U1 |
| 1 | Conn_01x04_Pin | Connector_Harwin:Harwin_M20-89004xx_1x04_P2.54mm_Horizontal | J2 |
| 1 | LED | LED_SMD:LED_0603_1608Metric | D1 |
| 1 | Simple_Addon_v2 | todbot_stuff:Simple_Addon_v2-SAO-2x3-minimal | J1 |
| 1 | ~ | todbot_eagle2023:TOUCHROTARY1B | TOUCH1 |
Questions
How big is the TouchwheelSAO PCB?
It measures 41 × 55.4 mm and has 2 copper layers, 1.6 mm thick.
What parts does the TouchwheelSAO use?
21 parts, built around the ATTINY816-MN and SK6812SIDE-A. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the TouchwheelSAO KiCad files?
From the todbot/TouchwheelSAO repository on GitHub, at the commit this page was made from: the board is schematics/TouchwheelSAO/TouchwheelSAO.kicad_pcb and its schematic schematics/TouchwheelSAO/TouchwheelSAO.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the TouchwheelSAO design in my own project?
Its repository publishes it under the GPL-3.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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